The present invention is directed in general to burners for gaseous fuels, and more particularly to a mixing plate which includes an outwardly protruding bulge at the center thereof.
Prior art burners for gaseous fuel are set forth, for example in British Pat. No. 1,044,235 to Eclipse Fuel Engineering, and in U.S. Pat. No. 4,340,180 to Belknap and Coppin, and the references cited therein.
Such prior art burners have been in general designed primarily for operation in ambient air streams, or relatively high oxygen, heated air streams. Such high oxygen air streams have in general contained at least 18% oxygen. However, in many present applications, the use of such previous burners is somewhat limited. In many instances, such burners have had to have been derated, and primary air utilized, or velocities have had to have been increased substantially. The net result of these modifications has greatly decreased system design flexibility for any particular use.
Also, prior art burner designs have required relatively large amounts of space. In some instances, as much as 0.70 sq. ft. per lineal foot of displacement have been required.
Yet further, prior art burners have not included adequate means for controlling or relieving pressure caused by thermal expansion during heating. As a result, the hinge points of the burner plates have undergone considerble stress, which greatly reduces plate life, and especially in certain harsh environments.
In view of the above difficulties, disadvantages and infirmities of prior art burner plates, it is an object of the improved burner unit of the present invention to materially alleviate such difficulties.
It is also an object of the improved burner unit of the present invention to provide an improved burner unit which may be utilized in relatively low oxygen air streams, and to provide flame retention, at rated capacity, over a much broader range of air stream conditions.
It is a concomitant object of the improved burner unit of the present invention to provide a burner unit which will function satisfactorily down to 800 feet per minute in ambient air, and in an air stream as low as 12% oxygen in a hot, oxygen deficient air stream at reasonable velocities without the need for primary air.
It is a further object of the improved burner unit of the present invention to reduce the displacement to as low as approximately 0.38 sq. ft. per lineal foot, and thus to provide a broader range of flexibility to the engineer in systems design and wherein such engineer may design the system without exceeding the allowable flame lengths or allowable pressure drops for such application.
It is a yet further object of the improved burner unit of the present invention to provide mixing plates of an unique shape, thereby to eliminate stress points caused by thermal expansion and contraction.
These and other objects of the improved burner unit of the present invention will be better understood by those having ordinary skill in the art, in view of the Summary of the Invention, Brief Description of the Drawing, Detailed Description of Preferred Embodiments, the attached Drawing, and the appended Claims.